Dam construction.



L. OHNSEN.

DAM COMSYUCTION.

@momma man nmz?, 1915.

lTNESSES: INVENTOR /gf MMM my@ @www ff ATTORNEYS L. R. IORGENSEN,

DAM CONSTRUCTION.

.APPLICATION FILED DEC.2T, I9I5.

` Patented Oct. 22,1918,

4 SHEETS-SHEET 3` w... QN .I w

Vr .n..u @QUESTI AmoRNEYS L. R. IORGENSEN.

DAM CONSTRUCTION.

APPLICATION FILED DEc.21.1915.

4 SHEETS-SMN 4.

Patented Oct. 22, 1918.

ORNE' LABS R. JORGENSEN, OF SOUTH BERKELEY, CALIFORNIA.

DAM. CONSTRUCTION.

Specication of Letters Patent.

Patented ct. 22, i918.

Application led December 27, 1915. Serial No. 68,680.

To all whom t may concern.'

Be it known that I, LARs R. JonGnNsEN, a citizen of the United States,residing at South Berkeley, in the county of Alameda and State ofCalifornia, have invented new and useful Improvements in DamConstruction, of which the following isa specification.

This invention relates to improvements in dams, and more particularly tomasonry dams of the arch type.

It consists in the construction of multiple arches, each arch having thecurvatures of the up-stream and down-stream portions, so designed thatthe lines of pressure coincide approximately with the axes of thearches. It also includes the strengthening of said arches by the use ofreinforcing steel and the semi-stiiiening of the buttresses. p

It also comprises details of construction which will be more fullyexplained by reference to the accompanying drawlngs, 1n which- Figure 1is a plan view of a multiple arch dam.

Fig. 2' is a down-stream elevation of the dam.

Fig. 3 isa partial section of the` arch, showing the method ofreinforcing.

Fig. 4 is a section on line 4 4 of Fig. 5.

Fig. 5 is a section on line 5-5 of Fig. 4.

Fig. 6 is a partial down-stream elevation of the arch and buttress,showing the reinforcement.

Fig. 7 is a section on line '7--7 of Fig. 5.

Fig. 8 shows a plan view of the device designed to allow water to flowover the crest.

Fig. 9 is asection on line 9--9 of Fig. 8.

Fig. 10 is a down-stream elevation of the device described in Fig. 8.

In cases where the caon sides are long, dat slopes toward the crest andmuch steeper toward the center. it will bey most economical to constructone large arch A in the middle, placing the buttresses 2 for the arch ator near the points where the slope changes. and constructing arches ofsmaller spans cn both sides to close the remainder of the gap. Thelength of the up-stream radius should. preferably, change in such a Waythat the inclosed angle is kept as constant as possible below `thebottom of the buttresses; that is, below the line a, Fig. 2, on thelarge arch t and below the line on the smaller arches.

The mrtion of the arches above the. lines a and respectively, should bedesigned as ordinary arches, either with sloping faces or verticalfaces; or in some places it may be economical to construct the largecentral arch with a substantial vertical faceand the smaller arches withsloping faces. lt may also be economical in places to make the lowerportion of the arch vertical, or nearly vertical, even above the bottomof the buttresses, and the remaining top portion of the arch sloping,regardless of whether the length of the up-stream radius is changed ornot, or whether all arches are of the same span or length.

Whenever the slope of the up-stream face of a multiple arch dam is.comparatively steep and the spanning comparatively short, thedifference of water pressure at the crown and at the abutments of thesame arch section is not so very great. The relative difference is, ofcourse, greatest at and near the crest. ln such a case it will beeconomical and most practical to change the circular shane of the archso that the center line of pressure coincides with the axis of the archtoward the crest only. where this deviation is the greatest as shown inFig. 1 of Patent #1.087.662 granted to me February 17, 1914) and thencontinue the arch as a circular arch at lower elevations where thisdeviation is small. ln places where this deviation is onlv small. andnot enough to warrant changing the shape of the arch. reinforcing steelshould be placed on the side liable to tension. as shown at 4. in Fig.3. along the hauuches on the down-stream side.

It mav also be advisablle. in places where the whole arch is reinforced.to shift the reinforcement in such a way outside and in-A side the axisof the dam that the steel is placed on the side liable to tension duringcold weather when the reservoir is empty, in the manner indicated at 4in Fig. 4; or it mav be necessary to place both these kinds ofreinforcements in the same structure, depending upon the stresses to betaken care of.

In order to strengthen the junction between the buttresses and arches ina multiple arch dam. reinforcing steel is placed in a vertical orsloping positiorr. as the case may be, in such a way as to form agirder. as shown in Figs. 4 and 5. ln Figs. 4 and 5 main rods 6 areshown with interconnecting tie rods. rThe number of these rods, however,is not material as any number might serve 'as Well. rThese rods areplaced in such a manner as to give the buttresses sucient strength towithstand an unbalanced arch push, such as Would occur should failure orpart failure of any adjacent arch taire place. The buttresses shouldalso be stildened with reinforcing steel 7, toward the down-stream edge,to take care of Wind pressure and the tendency ci large flat surfaces tocollapse.

At 7, as shown in Figs. Li, 5 and 6, is an arrangement of steel rods totake up anyy possible tension, due to Wind pressure or other causes. Thevertical steel bars 7 are tied together with horizontal or nearlyhorizontal steel rods in the usual manner.

lin order topstiifen the iiat vertical slab or buttress, reinforcedconcrete piers or counterforts are provided on each side. llihese piersor counterforts 10 are provided with reinforcing steel rods 1i in thesame manner as shown at 7, but in this case it is more eective, due tothe greater depth of the resulting girder 12. Above the strut elevationWhere there are no countertorts, reinforcing steel bars are placed inthe buttresses, as shown at 9, Figs. 5 and 7 to take care ol2 anycracking tendency that might develop in this part of the buttresses.

@n high dams additional reinforced piers or counterforts are necessarytoward the upstream `face, as the dat, comparatively thin buttressesbecome of large area. rlhese counteriforts may be given a slope towardthe up-stream face. rl`he reinforcement in the main struts 13 and 13,shown between the buttresses, should be thoroughly tied to thereinforcement in the buttresses, as the main object ci the struts is tostiften the Whole structure. 'ihe main struts should be capable ciwithstanding both tension and compression, besides bending. 'llo effectthis they are provided with secondary cross struts 1li and reinforcedknee-braces 15. At times they may act as supports for a bridge acrossthe individual arches.

'Whenever a multiple arch dam is to be designed to allow Tvater to :dowover its crest safely, such a device, as shown at 16, in liigs. 8, 9 andi0, Will be ci advantage. This.. consists ci a trough attached to thedown-stream face ci the dam, following the curvature of this as closelyas practical and provided with a horizontal slope toward the exit endfacilitate the rapid ifloiv ci Water. The exit i6 is to he at somediseutside the dawn-stream edge of the buttress so that the freeiiovving Water body Will reach the river entirely beyond the structurein a down-stream direction. A

pile of rock may also be placed to receive-f Having thus described myinvention, What Y i claim and desire to secure by Letters Patent is l. Amultiple arch dam having the junction of the arches and thecorresponding buttresses provided with reinforcing rods embedded in eacharch near the abutmens and in the buttress near the 11p-stream edge,said rods being hooped or connected together to orm a triangularstructure in each buttress and connected with a system of reinforcestruts located contiguous to the spring line of the arches.

2. in a multiple arch dam of the character described, a series of archeswith spans decreasing outwardly from the deepest portion of the streambed and the outermost arches sloping in an up-stream direction,buttresses uniting with the meeting ends of the arches, a triangularreinforcement of rods extending into the arches and abutments, and asystem of reinforced struts by Which the rods and structure are united.

3. nin a multiple arch dam of the characten described, an archreinforcement consisting of rods extending into the contiguous portionsci the arches and the abutments, said rods being hooped or tiedtogether, and a system of reinforced connecting struts with which thesaid hooped reinorcements are united.

t. in a multiple arch dam, a hooped rein- 'forcing structure, incombination vvith one or more lines of continuous struts located closeto the springing lines of the arches and anchored at opposite sides ofthe caon.

lin testimony vvhereoi l have hereunto set my hand in the presence citivo subscribing Witnesses.

LABS R. JGRGRNSEN.

.. Harrier.

Ato

